Conveyer chain



Nov. 7, 1950 J. K. MARSHALL EI'AL 2,529,163

' CONVEYER CHAIN Filed Oct. 8, 1948 2 Sheets-Sheet 1 T m, 20, f0; 0 a; 5

Patented Nov, 7, 195.0

CONVEYER CHAIN Joseph K. MarshalLChesterton, and Carl Nygren,

Michigan City, Ind., assignors to Michiana ProductsCorpr'ation, a corporation of Indiana Application October 8, 1948, Serial No. 53,506

3 Claims. (01. 198'189) Conveyor. chains used in many-heat treating furnaces. are subject. to high temperatures, often on the order of 1700 to.1800 degrees'Fahrenheit, and frequently heating and. cooling. For that reason, 'theyare made ofheat resisting alloy, and,

because such alloys are costly to work, the conveyor chains arecomposed of cast links u'n'hia chined except at the joints. Unavoidable foundry variations, manytiines amounting to as much asFAJ, bring about unwanted contact between thelinksof the chain and the sprocket teeth that result in destructive-wear. and strain.

The principalcobject. of. this invention is to make. allv foundry variationsjof link dimensions ineffective, and to provide smooth andaccurate working, otherwise obtainableonly byinachining so costly as to be prohibitive.-

Generally speaking, this is accomplished by making the chains'of center links (which alone take the drive) having a pitch greater than the pitch of the driving sprocket and connecting those center'links with side links having a pitch shorter than the pitch of the sprocket, and boring the pin holes in the center links in a fixture that insures accuracy with respect to the surface for contact with the sprocket teeth.

Other objects and advantages of the invention,

will appear as thedisclosure proceeds andv the description is read in connection with the accompanying drawings, in which Fig. 1 is a diagrammatic representation of a portion of a conveyor chain and a driving sprocket;

Fig. 2 is a plan view of a length of conveyor chain;

Fig. 3 is a similar plan view .of. a, length of conveyor chain. shortened to account for. stretch;

Fig. 4 is a diagrammatic representation of the teeth of the. driving sprocket and adjacent portions of center links shown in straight line relation;

Fig. 5 is a transverse section on the line 55 of Fig. 1;

Fig. 6 is a perspective view of one of the center links;

Fig. 7 is a perspective view of one of the side links, two of which make up a link between adjacent center links; and H v Fig. 8 is a perspective view of a change-over or take-up link usedin shortening the chain to correct for stretch.

Each centerlink H3,- shownin Fig. .6, is composed of cylindrical end portions I l and I2 connected by spaced side portions I3 pro giding a tooth space or socket l4 betweenthe cylindrical portions I land l2-and having outturned-fl anges l5-braced by gussetsl6 and forming the actual work support. f

The rounded surface not the cylindrical ,portion 12 0f each center link is in working contact with teeth of the driving sprocket; Byplading that surface ll against a suitable datum in a jig or fixture and boring the pin openings It at the appropriate distance with respect to each other and respect to that surface il, the pitch of that link is made accurate, notwithstanding any foundry. ari i q s. a d-th d tan e b tw e that surface ll and the similar'but idle -sur,

face 59 on the inside of the center link at the opposite end is such as to clear the tooth of the sprocket adjacent to that which is in contact with the surface I! in driving the chain.

Each-side link 20, shown in l ig g 'l is composed of cylindrical portions 2| and 22 connected by aweb or body 23 havingan out-turned flange 24 braced by a gusset 25. Each of'the cylindrical portions 2i and 22 is provided with a bored or drilled pin opening 26. Two side links, such as shown in Fig. '7, make up connecting linkbetween two adjacent center links, sho-wnin Fig. 6. The center and side links-are articulated by pins: 28- extending through the bores t8 and 26, as. shown in Fig. 5. The head :39 of each pin 23 has a bearing 39 for a roller 3!, and a bushing 32 welded to the opposite :end of the pin at 33- 7 provides a similar bearing for another roller 3|,

the rollers being on the outside of the links and having a diameter suitable for giving the chain support in its travel between sprockets.

In one embodiment of the invention that has been found satisfactory in practice; each center The rounded surface ll takes all the drive of the" s rocket, and it is theomy surface that re= ceive's the thrust of the sprocket tooth. By the" relationoi pitches and boring the 'pin iioiesjic' in a fix'ture having a, damn ng against the surface ii, each pitch line is definitely related to that surface i1. Each twelve inches of chain link is made accurate, and the surfaces Il and l are so spaced that there can be no binding between t e t eth and the links of the" sprocket chain.

is shorter than the sum of the pitches:

3 The static relation is represented in Fig. 1, where a tooth 35 on the driving sprocket 36 is in driving contact with the curved surface I! of the adjacent link l0, as indicated at 31. The next adjacent tooth 38 is received in the space or socket 14 between the side pieces l3 of the link l0, and is spaced from the curved surface IS on the inner side of the cylindrical portion ll approximately Thus, a foundry variation of is accomodated with the one-sixteenth of an inch clearance.

The next adjacent driving tooth 39 to the right is spaced from'the adjacent surface H by approximately A The next adjacent idle tooth 40 is spaced from the adjacent curved surface l9 approximately etc., until the idle tooth 42, which is about to leave the lower portion of the chain, is spaced from the adjacent curved surface l9 approximately 5".

With this arrangement, one tooth at a time transmits the driving force to the conveyor chain through the adjacent surface I! on one center link. As it takes the load, its predecessor in that oflice is relieved, and all other teeth of the sprocket are spaced from the adjacent surfaces. In particular, the idle teeth are spaced from the surfaces l9 far enough to prevent an possible binding between the idle tooth and those surfaces. Y

Heretofore, in standard chain designs for furnace conveyor chains, the front or pitch face of the idle teeth-have wedged against the surfaces corresponding to l9, putting enormous strains on the center links, tending to stretch them, grinding the sprockets, and forming a binding relation,

which resulted in the chain actually being lifted I at the bottom of the sprocket instead of falling away as it shouldand as is illustrated in Fig. 1.

In Fig. 4, the relation between the drlving tooth 35, the adjacent surface I! on the center link 10, the idle tooth 38, the adjacent surface I 9, the

next driving tooth 39, and the adjacent surface.

I! are represented in straight line relation to make the clearances stand out. Actually, when the chain is bent around the sprocket, there is some variation, but the clearances are still on the order of those indicated. There is always an increasing clearance between the front or pitch face of the sprocket teeth and the adjacent surface of the center link as the distance from the cylindrical portions 48 corresponding to the cylindrical portions 2| in Fig. '7, and spaced apart to correspond with two of those portions on a pair of side links. There is also an intermediate socket or space 49 corresponding to I4 in Fig. 6. The other features of the change-over link will be clear from the drawings Without further description. r Y

With such a link, slackv may be taken up by using it to replace one center link [0 and two side links 20, and connecting the cylindrical portions 48 to the adjacent cylindrical portion l2 of the center link and the cylindrical portion 46 with the adjacent cylindrical portions 2| of two side links by pins 28. This is shown in Fig. 3.

The change-over or take-up link 45 in the embodiment mentioned has a pitch of 6", or onehalf the sum of the pitches of the links H] and 20, with which it is to be used.

The arrow heads on Fig. 3 show the driving contact in the relevant portion of .the shortened chain, from which it will be noted that the drive is communicated to the rounded portion 4'! of the take-up link 45, and also the rounded portion H of the link Ill, to which it is connected.- Thus, ad acent links will take the drive in the shortened chain. g

' With the sprocket having an even number of teeth, the effect would be to cause a shift over to the alternate teeth, which had not been previously driving, or, as they have been called, idle.

driving contact of the one tooth represented by 35 increases. 7 g

The importance of relieving the strain produced by binding against the surfaces I9will become more clear when it is borne in'rnind that an alloy suitable for operation at temperatures on the order of 1700 degrees and having a tensile strength of 60,000 pounds cold should not be stressed over 750 pounds at the extreme temperature. Chains of standard design for this service may be expected to last four months, and they cost many'thousands of dollars.

All chains in conveyors for high temperature furnaces stretch in service and eventually become so slack that correction must be made. Ordinarily, that is done by taking out one link of a chain to shorten it. With the present arrangement, taking out'one link of a chain would result in difficulty in joining the two adjacent links, and, to get aronud that difliculty, a change-over or take-up link 45, shown in Fig. 8, is provided. It includes a cylindrical portion corresponding to the cylindrical portion I! in Fig. 6, and having a driving surface 41 corresponding to the driving surface" in Fig. 6. It also includes two But in case of a sprocket with an odd number of teeth, there would be little difference, since each revolution of the sprocket would cause a shift over from one set of teeth to another- We claim: 7

1. A conveyor chain .for use with a conventional sprocket of uniform pitch, said chain coinpr sing cast center links and cast side links, said center and side links alternating in sequence and being articulated together, the pitch of the center links being greater than that of the side links and the sum of the pitches of a pair of consecu tive links being greater twice the pitch of the.

sprocket.

2. In a heat treating furnace, a chain conveyor including a driving sprocket of uniform pitch, and a chain composed of center links and side links articulated together with the teeth of the sprocket driving the chain b pressure contact with the back of the center links only, the pitch of the sprocket being shorter than the pitch of the center link and longer than the pitch of the side links. f

3. In a heat treating furnace, a chain conveyor including a driving sprocket having uniform JOSEPH K. MARSHALL. CARL NYGREN.

REFERENCES CITED 7 The following references are of record in the file of this patent: I r

UNITED, STATES PATENTS Name 7 Number Date 

